Question: What are the space observatory which start with the letter x
Paraphrase: what are the space observatory which begins with  the letter x
SPARQL (Wikidata): SELECT DISTINCT ?sbj ?sbj_label WHERE { ?sbj wdt:P31 wd:Q148578 . ?sbj rdfs:label ?sbj_label . FILTER(STRSTARTS(lcase(?sbj_label), 'x')) . FILTER (lang(?sbj_label) = 'en') } LIMIT 25 
Answer: Xuntian, Xuntian, XPoSat, XPoSat, XEUS, XEUS, XMM-Newton, XMM-Newton